Not confirmed (thought it might have been mentioned in their press release), but I suspect the Gwangju plant in South Korea, the same plant that builds the Soul and Sportage. There are currently building it there for their domestic market and that is where it's suppose to come from for the global market (currently Australia, New Zealand)
I also heard about a possible build in Mexico, but I as South Korea is already in production with this model at this plant (capacity 600k units annually) it would only make sense to supply from there initially. The Mexican plant I think has an annual capacity of 300k units) and they are near capacity as to what they are currently building (2018 - 295,900 units built).
The Gwangju plant stop building the Rondo/Carens some time back so I would think they would have extra capacity there. The new India plant is basicly for their own market as they will be adding other models over the next year, again for that market.
www.seltosforum.com
I also heard about a possible build in Mexico, but I as South Korea is already in production with this model at this plant (capacity 600k units annually) it would only make sense to supply from there initially. The Mexican plant I think has an annual capacity of 300k units) and they are near capacity as to what they are currently building (2018 - 295,900 units built).
The Gwangju plant stop building the Rondo/Carens some time back so I would think they would have extra capacity there. The new India plant is basicly for their own market as they will be adding other models over the next year, again for that market.

Seltos Production/sales
Production - July 2019 Production started at the end of July at the all new Kia India plant where they built 234 units Production at the South Korean Gwangju plant: Domestic - 3,335 Export - 9